Experimental Study of Newtonian Laminar Annular Horizontal Displacement Flows With Rotating Inner Cylinder

Abstract

During the primary cementing of oil and gas wells, it is increasingly becoming common to slowly rotate the inner casing to aid the mud displacement. We present an experimental study of laminar horizontal displacement of Newtonian fluids with rotating inner cylinder with the experimental setup detailed in (Renteria et al., J. Fluid Mech, 905, 2020). Inner cylinder rotation is able to distort the axial flow to helical. When the rotational viscous force dominates buoyancy force, the displacing fluid follows the helical flow path and displaces the in situ fluid azimuthally around the annulus. The dimensionless rotational speed is defined as the ratio of rotational velocity and axial velocity, which determines the degree of azimuthal dispersion. Even in a buoyancy-dominant displacement, inner cylinder rotation acts to increase the dispersion. Displacement efficiency analysis shows that increasing rotational speed results in improved displacement. For high eccentricity cases, bottom side residual fluids are observed, which can easily be removed by rotating the inner cylinder. In practice, where the entire length of casing is rotated, the effect of rotation is expected to be more significant and improve the displacement.